Set during the chaotic days of World War I, a group of British soldiers get lost after a gruesome battle and step into a mysterious fog. Eventually the soldiers find a series of abandoned German trenches and discover in them many bodies of German soldiers wrapped in barbed wire. The group also discovers one German soldier who is still alive. The German soldier is subsequently tortured by all the British soldiers except for one quiet soldier named Charlie Shakespeare (Jamie Bell). During the night one British soldier, Barry Starinski, hears a noise and discovers the bodies of German soldiers wrapped in barbed wire. Meanwhile, another soldier, Jennings (Laurence Fox) begins to lose his mind. The rest of the British soldiers take refuge in the trenches and wait for help. Another British soldier, Thomas Quinn (Andy Serkis) takes his aggression out on the German prisoner who he ties up. The entire British unit eventually begins to turn on each other as their circumstances grow grimmer.